/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

/*
 * This package is based on the work done by Keiron Liddle, Aftex Software
 * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
 * great code.
 */
package org.apache.tools.bzip2;

import java.io.IOException;
import java.io.InputStream;

/**
 * An input stream that decompresses from the BZip2 format (without the file header chars) to be read as any other stream.
 * 
 * <p>
 * The decompression requires large amounts of memory. Thus you should call the {@link #close() close()} method as soon as possible, to force
 * <tt>CBZip2InputStream</tt> to release the allocated memory. See {@link CBZip2OutputStream CBZip2OutputStream} for information about memory usage.
 * </p>
 * 
 * <p>
 * <tt>CBZip2InputStream</tt> reads bytes from the compressed source stream via the single byte {@link java.io.InputStream#read() read()} method exclusively.
 * Thus you should consider to use a buffered source stream.
 * </p>
 * 
 * <p>
 * Instances of this class are not threadsafe.
 * </p>
 */
public class CBZip2InputStream extends InputStream implements BZip2Constants {

  private static void reportCRCError() {
    // The clean way would be to throw an exception.
    // throw new IOException("crc error");

    // Just print a message, like the previous versions of this class did
    System.err.println("BZip2 CRC error");
  }

  private void makeMaps() {
    final boolean[] inUse = this.data.inUse;
    final byte[] seqToUnseq = this.data.seqToUnseq;

    int nInUseShadow = 0;

    for (int i = 0; i < 256; i++) {
      if (inUse[i]) {
        seqToUnseq[nInUseShadow++] = (byte) i;
      }
    }

    this.nInUse = nInUseShadow;
  }

  /**
   * Index of the last char in the block, so the block size == last + 1.
   */
  private int                    last;

  /**
   * Index in zptr[] of original string after sorting.
   */
  private int                    origPtr;

  /**
   * always: in the range 0 .. 9. The current block size is 100000 * this number.
   */
  private int                    blockSize100k;

  private boolean                blockRandomised;

  private int                    bsBuff;
  private int                    bsLive;
  private final CRC              crc                  = new CRC();

  private int                    nInUse;

  private InputStream            in;

  private int                    currentChar          = -1;

  private static final int       EOF                  = 0;
  private static final int       START_BLOCK_STATE    = 1;
  private static final int       RAND_PART_A_STATE    = 2;
  private static final int       RAND_PART_B_STATE    = 3;
  private static final int       RAND_PART_C_STATE    = 4;
  private static final int       NO_RAND_PART_A_STATE = 5;
  private static final int       NO_RAND_PART_B_STATE = 6;
  private static final int       NO_RAND_PART_C_STATE = 7;

  private int                    currentState         = CBZip2InputStream.START_BLOCK_STATE;

  private int                    storedBlockCRC, storedCombinedCRC;
  private int                    computedBlockCRC, computedCombinedCRC;

  // Variables used by setup* methods exclusively

  private int                    su_count;
  private int                    su_ch2;
  private int                    su_chPrev;
  private int                    su_i2;
  private int                    su_j2;
  private int                    su_rNToGo;
  private int                    su_rTPos;
  private int                    su_tPos;
  private char                   su_z;

  /**
   * All memory intensive stuff. This field is initialized by initBlock().
   */
  private CBZip2InputStream.Data data;

  /**
   * Constructs a new CBZip2InputStream which decompresses bytes read from the specified stream.
   * 
   * <p>
   * Although BZip2 headers are marked with the magic <tt>"Bz"</tt> this constructor expects the next byte in the stream to be the first one after the magic.
   * Thus callers have to skip the first two bytes. Otherwise this constructor will throw an exception.
   * </p>
   * 
   * @throws IOException
   *           if the stream content is malformed or an I/O error occurs.
   * @throws NullPointerException
   *           if <tt>in == null</tt>
   */
  public CBZip2InputStream(final InputStream in) throws IOException {
    super();

    this.in = in;
    this.init();
  }

  @Override
  public int read() throws IOException {
    if (this.in != null) {
      return this.read0();
    } else {
      throw new IOException("stream closed");
    }
  }

  @Override
  public int read(final byte[] dest, final int offs, final int len) throws IOException {
    if (offs < 0) {
      throw new IndexOutOfBoundsException("offs(" + offs + ") < 0.");
    }
    if (len < 0) {
      throw new IndexOutOfBoundsException("len(" + len + ") < 0.");
    }
    if ((offs + len) > dest.length) {
      throw new IndexOutOfBoundsException("offs(" + offs + ") + len(" + len + ") > dest.length(" + dest.length + ").");
    }
    if (this.in == null) {
      throw new IOException("stream closed");
    }

    final int hi = offs + len;
    int destOffs = offs;
    for (int b; (destOffs < hi) && ((b = this.read0()) >= 0);) {
      dest[destOffs++] = (byte) b;
    }

    return (destOffs == offs) ? -1 : (destOffs - offs);
  }

  private int read0() throws IOException {
    final int retChar = this.currentChar;

    switch (this.currentState) {
      case EOF:
        return -1;

      case START_BLOCK_STATE:
        throw new IllegalStateException();

      case RAND_PART_A_STATE:
        throw new IllegalStateException();

      case RAND_PART_B_STATE:
        this.setupRandPartB();
        break;

      case RAND_PART_C_STATE:
        this.setupRandPartC();
        break;

      case NO_RAND_PART_A_STATE:
        throw new IllegalStateException();

      case NO_RAND_PART_B_STATE:
        this.setupNoRandPartB();
        break;

      case NO_RAND_PART_C_STATE:
        this.setupNoRandPartC();
        break;

      default:
        throw new IllegalStateException();
    }

    return retChar;
  }

  private void init() throws IOException {
    if (null == this.in) {
      throw new IOException("No InputStream");
    }
    if (this.in.available() == 0) {
      throw new IOException("Empty InputStream");
    }
    int magic2 = this.in.read();
    if (magic2 == 'B') {
      this.in.read();
      magic2 = this.in.read();
    }
    if (magic2 != 'h') {
      throw new IOException("Stream is not BZip2 formatted: expected 'h'" + " as first byte but got '" + (char) magic2 + "'");
    }

    final int blockSize = this.in.read();
    if ((blockSize < '1') || (blockSize > '9')) {
      throw new IOException("Stream is not BZip2 formatted: illegal " + "blocksize " + (char) blockSize);
    }

    this.blockSize100k = blockSize - '0';

    this.initBlock();
    this.setupBlock();
  }

  private void initBlock() throws IOException {
    final char magic0 = this.bsGetUByte();
    final char magic1 = this.bsGetUByte();
    final char magic2 = this.bsGetUByte();
    final char magic3 = this.bsGetUByte();
    final char magic4 = this.bsGetUByte();
    final char magic5 = this.bsGetUByte();

    if ((magic0 == 0x17) && (magic1 == 0x72) && (magic2 == 0x45) && (magic3 == 0x38) && (magic4 == 0x50) && (magic5 == 0x90)) {
      this.complete(); // end of file
    } else if ((magic0 != 0x31) || // '1'
        (magic1 != 0x41) || // ')'
        (magic2 != 0x59) || // 'Y'
        (magic3 != 0x26) || // '&'
        (magic4 != 0x53) || // 'S'
        (magic5 != 0x59 // 'Y'
        )) {
      this.currentState = CBZip2InputStream.EOF;
      throw new IOException("bad block header");
    } else {
      this.storedBlockCRC = this.bsGetInt();
      this.blockRandomised = this.bsR(1) == 1;

      /**
       * Allocate data here instead in constructor, so we do not allocate it if the input file is empty.
       */
      if (this.data == null) {
        this.data = new Data(this.blockSize100k);
      }

      // currBlockNo++;
      this.getAndMoveToFrontDecode();

      this.crc.initialiseCRC();
      this.currentState = CBZip2InputStream.START_BLOCK_STATE;
    }
  }

  private void endBlock() {
    this.computedBlockCRC = this.crc.getFinalCRC();

    // A bad CRC is considered a fatal error.
    if (this.storedBlockCRC != this.computedBlockCRC) {
      // make next blocks readable without error
      // (repair feature, not yet documented, not tested)
      this.computedCombinedCRC = (this.storedCombinedCRC << 1) | (this.storedCombinedCRC >>> 31);
      this.computedCombinedCRC ^= this.storedBlockCRC;

      CBZip2InputStream.reportCRCError();
    }

    this.computedCombinedCRC = (this.computedCombinedCRC << 1) | (this.computedCombinedCRC >>> 31);
    this.computedCombinedCRC ^= this.computedBlockCRC;
  }

  private void complete() throws IOException {
    this.storedCombinedCRC = this.bsGetInt();
    this.currentState = CBZip2InputStream.EOF;
    this.data = null;

    if (this.storedCombinedCRC != this.computedCombinedCRC) {
      CBZip2InputStream.reportCRCError();
    }
  }

  @Override
  public void close() throws IOException {
    final InputStream inShadow = this.in;
    if (inShadow != null) {
      try {
        if (inShadow != System.in) {
          inShadow.close();
        }
      } finally {
        this.data = null;
        this.in = null;
      }
    }
  }

  private int bsR(final int n) throws IOException {
    int bsLiveShadow = this.bsLive;
    int bsBuffShadow = this.bsBuff;

    if (bsLiveShadow < n) {
      final InputStream inShadow = this.in;
      do {
        final int thech = inShadow.read();

        if (thech < 0) {
          throw new IOException("unexpected end of stream");
        }

        bsBuffShadow = (bsBuffShadow << 8) | thech;
        bsLiveShadow += 8;
      } while (bsLiveShadow < n);

      this.bsBuff = bsBuffShadow;
    }

    this.bsLive = bsLiveShadow - n;
    return (bsBuffShadow >> (bsLiveShadow - n)) & ((1 << n) - 1);
  }

  private boolean bsGetBit() throws IOException {
    int bsLiveShadow = this.bsLive;
    int bsBuffShadow = this.bsBuff;

    if (bsLiveShadow < 1) {
      final int thech = this.in.read();

      if (thech < 0) {
        throw new IOException("unexpected end of stream");
      }

      bsBuffShadow = (bsBuffShadow << 8) | thech;
      bsLiveShadow += 8;
      this.bsBuff = bsBuffShadow;
    }

    this.bsLive = bsLiveShadow - 1;
    return ((bsBuffShadow >> (bsLiveShadow - 1)) & 1) != 0;
  }

  private char bsGetUByte() throws IOException {
    return (char) this.bsR(8);
  }

  private int bsGetInt() throws IOException {
    return (((((this.bsR(8) << 8) | this.bsR(8)) << 8) | this.bsR(8)) << 8) | this.bsR(8);
  }

  /**
   * Called by createHuffmanDecodingTables() exclusively.
   */
  private static void hbCreateDecodeTables(final int[] limit, final int[] base, final int[] perm, final char[] length, final int minLen, final int maxLen,
      final int alphaSize) {
    for (int i = minLen, pp = 0; i <= maxLen; i++) {
      for (int j = 0; j < alphaSize; j++) {
        if (length[j] == i) {
          perm[pp++] = j;
        }
      }
    }

    for (int i = BZip2Constants.MAX_CODE_LEN; --i > 0;) {
      base[i] = 0;
      limit[i] = 0;
    }

    for (int i = 0; i < alphaSize; i++) {
      base[length[i] + 1]++;
    }

    for (int i = 1, b = base[0]; i < BZip2Constants.MAX_CODE_LEN; i++) {
      b += base[i];
      base[i] = b;
    }

    for (int i = minLen, vec = 0, b = base[i]; i <= maxLen; i++) {
      final int nb = base[i + 1];
      vec += nb - b;
      b = nb;
      limit[i] = vec - 1;
      vec <<= 1;
    }

    for (int i = minLen + 1; i <= maxLen; i++) {
      base[i] = ((limit[i - 1] + 1) << 1) - base[i];
    }
  }

  private void recvDecodingTables() throws IOException {
    final Data dataShadow = this.data;
    final boolean[] inUse = dataShadow.inUse;
    final byte[] pos = dataShadow.recvDecodingTables_pos;
    final byte[] selector = dataShadow.selector;
    final byte[] selectorMtf = dataShadow.selectorMtf;

    int inUse16 = 0;

    /* Receive the mapping table */
    for (int i = 0; i < 16; i++) {
      if (this.bsGetBit()) {
        inUse16 |= 1 << i;
      }
    }

    for (int i = 256; --i >= 0;) {
      inUse[i] = false;
    }

    for (int i = 0; i < 16; i++) {
      if ((inUse16 & (1 << i)) != 0) {
        final int i16 = i << 4;
        for (int j = 0; j < 16; j++) {
          if (this.bsGetBit()) {
            inUse[i16 + j] = true;
          }
        }
      }
    }

    this.makeMaps();
    final int alphaSize = this.nInUse + 2;

    /* Now the selectors */
    final int nGroups = this.bsR(3);
    final int nSelectors = this.bsR(15);

    for (int i = 0; i < nSelectors; i++) {
      int j = 0;
      while (this.bsGetBit()) {
        j++;
      }
      selectorMtf[i] = (byte) j;
    }

    /* Undo the MTF values for the selectors. */
    for (int v = nGroups; --v >= 0;) {
      pos[v] = (byte) v;
    }

    for (int i = 0; i < nSelectors; i++) {
      int v = selectorMtf[i] & 0xff;
      final byte tmp = pos[v];
      while (v > 0) {
        // nearly all times v is zero, 4 in most other cases
        pos[v] = pos[v - 1];
        v--;
      }
      pos[0] = tmp;
      selector[i] = tmp;
    }

    final char[][] len = dataShadow.temp_charArray2d;

    /* Now the coding tables */
    for (int t = 0; t < nGroups; t++) {
      int curr = this.bsR(5);
      final char[] len_t = len[t];
      for (int i = 0; i < alphaSize; i++) {
        while (this.bsGetBit()) {
          curr += this.bsGetBit() ? -1 : 1;
        }
        len_t[i] = (char) curr;
      }
    }

    // finally create the Huffman tables
    this.createHuffmanDecodingTables(alphaSize, nGroups);
  }

  /**
   * Called by recvDecodingTables() exclusively.
   */
  private void createHuffmanDecodingTables(final int alphaSize, final int nGroups) {
    final Data dataShadow = this.data;
    final char[][] len = dataShadow.temp_charArray2d;
    final int[] minLens = dataShadow.minLens;
    final int[][] limit = dataShadow.limit;
    final int[][] base = dataShadow.base;
    final int[][] perm = dataShadow.perm;

    for (int t = 0; t < nGroups; t++) {
      int minLen = 32;
      int maxLen = 0;
      final char[] len_t = len[t];
      for (int i = alphaSize; --i >= 0;) {
        final char lent = len_t[i];
        if (lent > maxLen) {
          maxLen = lent;
        }
        if (lent < minLen) {
          minLen = lent;
        }
      }
      CBZip2InputStream.hbCreateDecodeTables(limit[t], base[t], perm[t], len[t], minLen, maxLen, alphaSize);
      minLens[t] = minLen;
    }
  }

  private void getAndMoveToFrontDecode() throws IOException {
    this.origPtr = this.bsR(24);
    this.recvDecodingTables();

    final InputStream inShadow = this.in;
    final Data dataShadow = this.data;
    final byte[] ll8 = dataShadow.ll8;
    final int[] unzftab = dataShadow.unzftab;
    final byte[] selector = dataShadow.selector;
    final byte[] seqToUnseq = dataShadow.seqToUnseq;
    final char[] yy = dataShadow.getAndMoveToFrontDecode_yy;
    final int[] minLens = dataShadow.minLens;
    final int[][] limit = dataShadow.limit;
    final int[][] base = dataShadow.base;
    final int[][] perm = dataShadow.perm;
    final int limitLast = this.blockSize100k * 100000;

    /*
     * Setting up the unzftab entries here is not strictly necessary, but it does save having to do it later in a separate pass, and so saves a block's worth of
     * cache misses.
     */
    for (int i = 256; --i >= 0;) {
      yy[i] = (char) i;
      unzftab[i] = 0;
    }

    int groupNo = 0;
    int groupPos = BZip2Constants.G_SIZE - 1;
    final int eob = this.nInUse + 1;
    int nextSym = this.getAndMoveToFrontDecode0(0);
    int bsBuffShadow = this.bsBuff;
    int bsLiveShadow = this.bsLive;
    int lastShadow = -1;
    int zt = selector[groupNo] & 0xff;
    int[] base_zt = base[zt];
    int[] limit_zt = limit[zt];
    int[] perm_zt = perm[zt];
    int minLens_zt = minLens[zt];

    while (nextSym != eob) {
      if ((nextSym == BZip2Constants.RUNA) || (nextSym == BZip2Constants.RUNB)) {
        int s = -1;

        for (int n = 1; true; n <<= 1) {
          if (nextSym == BZip2Constants.RUNA) {
            s += n;
          } else if (nextSym == BZip2Constants.RUNB) {
            s += n << 1;
          } else {
            break;
          }

          if (groupPos == 0) {
            groupPos = BZip2Constants.G_SIZE - 1;
            zt = selector[++groupNo] & 0xff;
            base_zt = base[zt];
            limit_zt = limit[zt];
            perm_zt = perm[zt];
            minLens_zt = minLens[zt];
          } else {
            groupPos--;
          }

          int zn = minLens_zt;

          // Inlined:
          // int zvec = bsR(zn);
          while (bsLiveShadow < zn) {
            final int thech = inShadow.read();
            if (thech >= 0) {
              bsBuffShadow = (bsBuffShadow << 8) | thech;
              bsLiveShadow += 8;
              continue;
            } else {
              throw new IOException("unexpected end of stream");
            }
          }
          int zvec = (bsBuffShadow >> (bsLiveShadow - zn)) & ((1 << zn) - 1);
          bsLiveShadow -= zn;

          while (zvec > limit_zt[zn]) {
            zn++;
            while (bsLiveShadow < 1) {
              final int thech = inShadow.read();
              if (thech >= 0) {
                bsBuffShadow = (bsBuffShadow << 8) | thech;
                bsLiveShadow += 8;
                continue;
              } else {
                throw new IOException("unexpected end of stream");
              }
            }
            bsLiveShadow--;
            zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
          }
          nextSym = perm_zt[zvec - base_zt[zn]];
        }

        final byte ch = seqToUnseq[yy[0]];
        unzftab[ch & 0xff] += s + 1;

        while (s-- >= 0) {
          ll8[++lastShadow] = ch;
        }

        if (lastShadow >= limitLast) {
          throw new IOException("block overrun");
        }
      } else {
        if (++lastShadow >= limitLast) {
          throw new IOException("block overrun");
        }

        final char tmp = yy[nextSym - 1];
        unzftab[seqToUnseq[tmp] & 0xff]++;
        ll8[lastShadow] = seqToUnseq[tmp];

        /*
         * This loop is hammered during decompression, hence avoid native method call overhead of System.arraycopy for very small ranges to copy.
         */
        if (nextSym <= 16) {
          for (int j = nextSym - 1; j > 0;) {
            yy[j] = yy[--j];
          }
        } else {
          System.arraycopy(yy, 0, yy, 1, nextSym - 1);
        }

        yy[0] = tmp;

        if (groupPos == 0) {
          groupPos = BZip2Constants.G_SIZE - 1;
          zt = selector[++groupNo] & 0xff;
          base_zt = base[zt];
          limit_zt = limit[zt];
          perm_zt = perm[zt];
          minLens_zt = minLens[zt];
        } else {
          groupPos--;
        }

        int zn = minLens_zt;

        // Inlined:
        // int zvec = bsR(zn);
        while (bsLiveShadow < zn) {
          final int thech = inShadow.read();
          if (thech >= 0) {
            bsBuffShadow = (bsBuffShadow << 8) | thech;
            bsLiveShadow += 8;
            continue;
          } else {
            throw new IOException("unexpected end of stream");
          }
        }
        int zvec = (bsBuffShadow >> (bsLiveShadow - zn)) & ((1 << zn) - 1);
        bsLiveShadow -= zn;

        while (zvec > limit_zt[zn]) {
          zn++;
          while (bsLiveShadow < 1) {
            final int thech = inShadow.read();
            if (thech >= 0) {
              bsBuffShadow = (bsBuffShadow << 8) | thech;
              bsLiveShadow += 8;
              continue;
            } else {
              throw new IOException("unexpected end of stream");
            }
          }
          bsLiveShadow--;
          zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
        }
        nextSym = perm_zt[zvec - base_zt[zn]];
      }
    }

    this.last = lastShadow;
    this.bsLive = bsLiveShadow;
    this.bsBuff = bsBuffShadow;
  }

  private int getAndMoveToFrontDecode0(final int groupNo) throws IOException {
    final InputStream inShadow = this.in;
    final Data dataShadow = this.data;
    final int zt = dataShadow.selector[groupNo] & 0xff;
    final int[] limit_zt = dataShadow.limit[zt];
    int zn = dataShadow.minLens[zt];
    int zvec = this.bsR(zn);
    int bsLiveShadow = this.bsLive;
    int bsBuffShadow = this.bsBuff;

    while (zvec > limit_zt[zn]) {
      zn++;
      while (bsLiveShadow < 1) {
        final int thech = inShadow.read();

        if (thech >= 0) {
          bsBuffShadow = (bsBuffShadow << 8) | thech;
          bsLiveShadow += 8;
          continue;
        } else {
          throw new IOException("unexpected end of stream");
        }
      }
      bsLiveShadow--;
      zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
    }

    this.bsLive = bsLiveShadow;
    this.bsBuff = bsBuffShadow;

    return dataShadow.perm[zt][zvec - dataShadow.base[zt][zn]];
  }

  private void setupBlock() throws IOException {
    if (this.data == null) {
      return;
    }

    final int[] cftab = this.data.cftab;
    final int[] tt = this.data.initTT(this.last + 1);
    final byte[] ll8 = this.data.ll8;
    cftab[0] = 0;
    System.arraycopy(this.data.unzftab, 0, cftab, 1, 256);

    for (int i = 1, c = cftab[0]; i <= 256; i++) {
      c += cftab[i];
      cftab[i] = c;
    }

    for (int i = 0, lastShadow = this.last; i <= lastShadow; i++) {
      tt[cftab[ll8[i] & 0xff]++] = i;
    }

    if ((this.origPtr < 0) || (this.origPtr >= tt.length)) {
      throw new IOException("stream corrupted");
    }

    this.su_tPos = tt[this.origPtr];
    this.su_count = 0;
    this.su_i2 = 0;
    this.su_ch2 = 256; /* not a char and not EOF */

    if (this.blockRandomised) {
      this.su_rNToGo = 0;
      this.su_rTPos = 0;
      this.setupRandPartA();
    } else {
      this.setupNoRandPartA();
    }
  }

  private void setupRandPartA() throws IOException {
    if (this.su_i2 <= this.last) {
      this.su_chPrev = this.su_ch2;
      int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
      this.su_tPos = this.data.tt[this.su_tPos];
      if (this.su_rNToGo == 0) {
        this.su_rNToGo = BZip2Constants.rNums[this.su_rTPos] - 1;
        if (++this.su_rTPos == 512) {
          this.su_rTPos = 0;
        }
      } else {
        this.su_rNToGo--;
      }
      this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0;
      this.su_i2++;
      this.currentChar = su_ch2Shadow;
      this.currentState = CBZip2InputStream.RAND_PART_B_STATE;
      this.crc.updateCRC(su_ch2Shadow);
    } else {
      this.endBlock();
      this.initBlock();
      this.setupBlock();
    }
  }

  private void setupNoRandPartA() throws IOException {
    if (this.su_i2 <= this.last) {
      this.su_chPrev = this.su_ch2;
      final int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
      this.su_ch2 = su_ch2Shadow;
      this.su_tPos = this.data.tt[this.su_tPos];
      this.su_i2++;
      this.currentChar = su_ch2Shadow;
      this.currentState = CBZip2InputStream.NO_RAND_PART_B_STATE;
      this.crc.updateCRC(su_ch2Shadow);
    } else {
      this.currentState = CBZip2InputStream.NO_RAND_PART_A_STATE;
      this.endBlock();
      this.initBlock();
      this.setupBlock();
    }
  }

  private void setupRandPartB() throws IOException {
    if (this.su_ch2 != this.su_chPrev) {
      this.currentState = CBZip2InputStream.RAND_PART_A_STATE;
      this.su_count = 1;
      this.setupRandPartA();
    } else if (++this.su_count >= 4) {
      this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
      this.su_tPos = this.data.tt[this.su_tPos];
      if (this.su_rNToGo == 0) {
        this.su_rNToGo = BZip2Constants.rNums[this.su_rTPos] - 1;
        if (++this.su_rTPos == 512) {
          this.su_rTPos = 0;
        }
      } else {
        this.su_rNToGo--;
      }
      this.su_j2 = 0;
      this.currentState = CBZip2InputStream.RAND_PART_C_STATE;
      if (this.su_rNToGo == 1) {
        this.su_z ^= 1;
      }
      this.setupRandPartC();
    } else {
      this.currentState = CBZip2InputStream.RAND_PART_A_STATE;
      this.setupRandPartA();
    }
  }

  private void setupRandPartC() throws IOException {
    if (this.su_j2 < this.su_z) {
      this.currentChar = this.su_ch2;
      this.crc.updateCRC(this.su_ch2);
      this.su_j2++;
    } else {
      this.currentState = CBZip2InputStream.RAND_PART_A_STATE;
      this.su_i2++;
      this.su_count = 0;
      this.setupRandPartA();
    }
  }

  private void setupNoRandPartB() throws IOException {
    if (this.su_ch2 != this.su_chPrev) {
      this.su_count = 1;
      this.setupNoRandPartA();
    } else if (++this.su_count >= 4) {
      this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
      this.su_tPos = this.data.tt[this.su_tPos];
      this.su_j2 = 0;
      this.setupNoRandPartC();
    } else {
      this.setupNoRandPartA();
    }
  }

  private void setupNoRandPartC() throws IOException {
    if (this.su_j2 < this.su_z) {
      final int su_ch2Shadow = this.su_ch2;
      this.currentChar = su_ch2Shadow;
      this.crc.updateCRC(su_ch2Shadow);
      this.su_j2++;
      this.currentState = CBZip2InputStream.NO_RAND_PART_C_STATE;
    } else {
      this.su_i2++;
      this.su_count = 0;
      this.setupNoRandPartA();
    }
  }

  private static final class Data extends Object {

    // (with blockSize 900k)
    final boolean[] inUse                      = new boolean[256];                                                // 256 byte

    final byte[]    seqToUnseq                 = new byte[256];                                                   // 256 byte
    final byte[]    selector                   = new byte[BZip2Constants.MAX_SELECTORS];                          // 18002 byte
    final byte[]    selectorMtf                = new byte[BZip2Constants.MAX_SELECTORS];                          // 18002 byte

    /**
     * Freq table collected to save a pass over the data during decompression.
     */
    final int[]     unzftab                    = new int[256];                                                    // 1024 byte

    final int[][]   limit                      = new int[BZip2Constants.N_GROUPS][BZip2Constants.MAX_ALPHA_SIZE]; // 6192 byte
    final int[][]   base                       = new int[BZip2Constants.N_GROUPS][BZip2Constants.MAX_ALPHA_SIZE]; // 6192 byte
    final int[][]   perm                       = new int[BZip2Constants.N_GROUPS][BZip2Constants.MAX_ALPHA_SIZE]; // 6192 byte
    final int[]     minLens                    = new int[BZip2Constants.N_GROUPS];                                // 24 byte

    final int[]     cftab                      = new int[257];                                                    // 1028 byte
    final char[]    getAndMoveToFrontDecode_yy = new char[256];                                                   // 512 byte
    final char[][]  temp_charArray2d           = new char[BZip2Constants.N_GROUPS][BZip2Constants.MAX_ALPHA_SIZE]; // 3096 byte
    final byte[]    recvDecodingTables_pos     = new byte[BZip2Constants.N_GROUPS];                               // 6 byte
    // ---------------
    // 60798 byte

    int[]           tt;                                                                                           // 3600000 byte
    byte[]          ll8;                                                                                          // 900000 byte

    // ---------------
    // 4560782 byte
    // ===============

    Data(final int blockSize100k) {
      super();

      this.ll8 = new byte[blockSize100k * BZip2Constants.baseBlockSize];
    }

    /**
     * Initializes the {@link #tt} array.
     * 
     * This method is called when the required length of the array is known. I don't initialize it at construction time to avoid unneccessary memory allocation
     * when compressing small files.
     */
    final int[] initTT(final int length) {
      int[] ttShadow = this.tt;

      // tt.length should always be >= length, but theoretically
      // it can happen, if the compressor mixed small and large
      // blocks. Normally only the last block will be smaller
      // than others.
      if ((ttShadow == null) || (ttShadow.length < length)) {
        this.tt = ttShadow = new int[length];
      }

      return ttShadow;
    }

  }
}
